Precision positioning of the roll to a coordinate system devised for that roll That is if the paper roll is 35 meters long or 35'000 mm and 914.4mm wide I could choose a point on that roll say x=10567 and y=804 (where x=1 is 1mm offset y=1 is 1mm offset on the y axis) and have that point moved to a specific spot on the part of the roll between the shafts that is stretched and forms a long visible surface(writable with pen or other means area).

Imagine the distance between the two rolls increased significantly and the first roll of paper tuck in or be held on the second spindle/shaft.... The idea is to be able to roll back and forth from the left roll to the right so as to achieve a precise positioning to a specific portion within the roll. The position requested by choosing a point on the entire roll i.e. 3'500 mm(3 metres and 50 cm) on x and have that be scrolled right in the centre between the 2 rolls. So if the distance between the 2 roll holders is 2 metres The point on the roll of 3'500mm should be positioned to the middle point which is a point spaced 1 metre from either scrolls.When I lay out the entire paper roll the surface gets the dimensions of about 35metres and 914mm.I have:

Arduino compatible board

Raspberry pi

Laptop (Ubuntu Linux)

I need ideas on the shaft , bearings and precision positioning of the paper through rotary or linear encoders etc...